This invention relates to impregnation and encapsulation of capacitors.
Dry capacitors are generally constructed by encapsulating the capacitor winding in a rigid material such as epoxy or polyurethane. Wet capacitors, on the other hand, are typically encapsulated by a dielectric liquid, such as polybutene (Lapp et al., U.S. Pat. No. 3,996,505). Wet capacitors are typically housed in sealed cans and include pressure sensitive interruption devices that operate on gas pressure built up within the can as the capacitor begins to fail.
Siemens et al., British patent No. 191,449, describes a capacitor impregnated with a mixture of low molecular weight polyisobutylene and lanosterol.
Holzinger, U.S. Pat. No. 3,402,237, describes a thermosetting composition for encapsulating electrical conductors. The composition is a mixture of isobutylenes, conjugated drying oils, liquid extenders, solid particulate extenders, and a catalyst.
Another thermosetting composition, described in MacKenzie, U.S. Pat. No. 4,020,214, consists of a mixture of ethylene containing polymers, a cross-linking curing agent, a mineral filler, and an organic titanate.